Tape-Measure Mapper

Well, I'm sure there's a better way to do this, but it's an
excuse to dust off my Javascript and SVG skills...

This tool allows you to accurately sketch out a room or other
area based on tape-measure measurements. Measure the length of
the walls and at least one diagonal and you can accurately
figure out the geometry of the place, even if the walls aren't
square. I wrote it in order to figure out how to cram all my
furniture into my decidedly non-rectangular bedroom:

The way you use it is as follows. First, lay out some points.

Link them together with lines representing the walls

Add some measurements. You want to have a network of triangles,
so that every point is uniquely constrained.

Turn on error bars. This uses red bars to show you how far out
your points are.

Shuffle the points around manually to get things basically
right.

Turn on "Snap to Measurements". The program automatically
shuffles the points around as best it can to minimise the
errors.

Click on "Export to SVG". This is the weakest part of the
program: all it does is build a giant text area full of raw SVG
code. Cut that text, paste it into a text file with a ".svg"
filename extension. You should be able to open the resulting
file in Inkscape.

And that's it. Here's the script.
It's just an SVG file with embedded Javascript, so you can save
it and use it offline if you want to.